1. Field of the Invention
The present invention relates to an entertainment system comprising a portable information terminal and an entertainment apparatus to which the portable information terminal is detachably connectable, a cell charging system comprising a portable information terminal and a portable information terminal host, an entertainment apparatus to which a portable information terminal is detachably connectable, a portable information terminal detachably connectable to an entertainment apparatus, and an external cell charger for charging a cell of a portable information terminal.
2. Description of the Related Art
Recently, portable information terminals, also known as PDA (Personal Digital Assistant), which have a flat display panel such as a liquid crystal display panel, such as portable computers, electronic notepads, portable telephone sets, PHS (Personal Handy-phone System) terminals, pagers, or the like have widely been used in the art.
Such a portable information terminal may be connected to a notebook-type personal computer or a stationary computer for data transfer to and from the computer.
Entertainment apparatus for downloading a program from a mass storage medium such as a CD-ROM as an optical disk and executing a game according to the downloaded program, or playing back music based on data from a CD have also been in widespread use.
There have commercially been available portable information terminals that can detachably be connected to such entertainment apparatus for downloading a program via the entertainment apparatus and executing a game according to the downloaded program by themselves.
Batteries incorporated in portable information terminals for energizing them are generally primary batteries because the primary batteries have a cell capacity several times greater than chargeable secondary batteries of the same volume and hence allow the portable information terminals to operate for a longer period of time.
If a secondary cell is incorporated in a portable information terminal, then the secondary cell is charged by an external cell charger which is supplied with an AC power supply and dedicated for charging the secondary cell.
The portable information terminals powered by primary batteries are disadvantageous that the primary cell needs to be replaced with a new one each time it is used up.
Use of the external cell charger dedicated for charging the secondary cell with the AC power supply is costly because the external cell charger needs to have dedicated circuits including an AC-to-DC converter.